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Rear Axle Installation Issue

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Rear Axle Installation Issue
#1
  This topic is about my 1960 MG MGA 1600
hursst Silver Member Chris L
Woodbridge, VA, USA   USA
Spent 5 very unproductive hours in the garage today trying to re-assemble my rear axle, and accomplished almost nothing. Have a very frustrating issue that maybe someone could help me solve.

A few weeks ago, I re-installed my passenger side rear axle hub bearing assembly using a new hub nut. I found that when I originally tightened this nut to 150 ft lbs, the hub locked up tight and could not be moved. I backed off the nut, made some adjustments to the backing washer, and tried again. Eventually I got it to where the hub was moving, but it was binding slightly, but not bad.

Fast forward to today, I installed the ring and pinion carrier into the rear axle, but just put the nuts on finger tight for now. I then proceeded to install the driver's side rear axle hub bearing assembly with a new left-threaded hub nut. Again, the hub locked up tight with some torque applied to the hub nut. I could not get this hub free without pulling the hub bearing assembly out a little, then it spun fine. I took the whole thing apart, brake backing plate and all, and I believe the issue is that the new nut is slightly too tall and is pressing the far end of the hub bearing assembly into the axle flange, where the brake backing plate is attached, which keeps the hub from spinning.

I then dug out my original hub nuts, and re-installed them on both sides of the axle, and sure enough, the hubs now turn freely even with 150 lbs. of torque applied to the hub nuts. The new Moss octagonal hub nuts are slightly too thick, I believe. However, that's not my main issue, just wanted to provide some background.

Once I got these hubs installed using the original nuts, I tried to install the rear axles themselves. I slid them both on, matched up the splines from axle to the ring and pinion assembly and both of them stopped short of mating with the hub bearing assembly and paper gasket by about 1.5 to 2mm.

It feels like the insides of the inner axles are hitting the hub nut and not allowing the axles to go all the way in. It's a very solid stop, it doesn't feel like binding. It is happening on both sides of the axle assembly. At this point, I threw up my hands and I couldn't believe this was happening and came back inside.

Any ideas on what could possibly be causing this issue? I'm completely flabbergasted, but hoping it's something stupid or easy that I missed. Any help, as usual, is greatly appreciated.

-Chris

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dmccann David McCann
Springfield, ,OH/Richmond,VA/San Francisco,CA, USA   USA
1960 MG MGA
1964 MG MGB
1969 MG MGB GT
1970 MG MGB    & more
I'm not following exactly what you're describing, but I don't see how the new nuts can be causing the first of the two problems you are describing. If they are thicker along the axis then that should not do what you describe. If they are thicker radially, then they would be too big for the 1 61/64" wrench.

What parts are original and what parts have you replaced? The axle half-shafts are original to the axle housing? Did you replace the wire wheel hub, or is this a disk wheel car?

hursst Silver Member Chris L
Woodbridge, VA, USA   USA
Thanks for the response. The new nuts appear to be slightly thicker on the axis. I have not measured them, just a visual comparison. I'm also making an assumption based on the fact that when I used these new nuts, when I torqued them down, the hubs locked up completely. The reason for them locking up is that the part of the hub bearing assembly furthest away from you when you put the assembly on the axle hub will eventually hit the back portion of the axle hub where it meets the flange attached to the axle tube and lock itself there with friction. I was able to slightly move the hub bearing assembly with a large rubber mallet a few times. When I took the whole thing apart again, you could tell this area was affected as it was shinny metal and there were some fine metal shavings there from when I was able to slightly move the hub. This problem has been solved by me going back to the original hub nuts.

This is a wire wheel car. The only things I've replaced are the inner hub bearing and seals on both sides, the O-rings, and gaskets. Everything else is original, just cleaned up. I had the ring and pinion carrier assembly taken to a shop and they replaced the pinion bearing and tested the backlash, which was in spec.

The bottom line is, the axle half-shaft assembly is not seating to the hub bearing assembly and is off by about 2mm on the passenger side and 1mm on the driver's side. See photo, you can see an air gap between them, the photo being the passenger side. It will not go in any further. This happens with or without the O-ring, so I know it's not too thick of an O-ring that's causing it. Everything looked correct when I took it apart, so obviously something has changed or I am missing something, but I cannot figure it out; it looks like it should work. The only thin I can think of is that the inner part of the axle half shaft is contacting the hub nut in some way, preventing it from going all the way on.

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barneymg Avatar
barneymg Barney Gaylord
(Somewhere in USA), Pick one (or more), USA   USA
1958 MG MGA "MGA With An Attitude"
That could be the ball bearing is not completely seated in the rotating hub. Or, if you changed the splined hubs, they may bot be pressed far enough onto the halfshafts, so the halfshafts hit the pinion shaft in the differential.



Barney Gaylord - 1958 MGA with an attitude - http://MGAguru.com - barneymg@mgaguru.com

dmccann David McCann
Springfield, ,OH/Richmond,VA/San Francisco,CA, USA   USA
1960 MG MGA
1964 MG MGB
1969 MG MGB GT
1970 MG MGB    & more
Thank you for the additional information. This reinforces what I was thinking before, which is that there is no way the nuts can be making the hubs lock up. I can not say why the original nuts do not make the bearing hubs lock up, but something is causing the bearing hubs to be inboard of where they should be. Because of this, the inside of the hubs rub and the spline hubs do not meet up with the bearing hub. I don't recall how possible this is or what might cause it, but it seems like the bearings are not fully pressed into the bearing hubs.

dmccann David McCann
Springfield, ,OH/Richmond,VA/San Francisco,CA, USA   USA
1960 MG MGA
1964 MG MGB
1969 MG MGB GT
1970 MG MGB    & more
I see Barney slipped an answer in while I was writing mine. It's good to see I was on the same track as him. His second answer of the splined hub not being pressed on fully is something that I have had happen, and could certainly cause the flanges to not meet up, but it would have nothing to do with the bearing hub locking up when the new nuts were fully tightened. But I also don't have an answer for why the old nuts don't cause that problem. You are tightening those down fully, right. At least 150 ft/lbs, and I don't think over tightening is a problem there.

Richard555 Avatar
Richard555 Richard Kenyon
Alexandria, Canada   CAN

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hursst Silver Member Chris L
Woodbridge, VA, USA   USA
Thank you for the responses. The only thing that changed with this whole assembly are the inner bearings and seals in the hub bearing assembly, so the answer of the bearing(s) not being seated properly must be the answer. I'll pull the hub bearing assemblies again and see if I can figure out exactly how I messed this up. I don't fully understand the physics behind how the hub is secured on the axle tube, either, so I think I really have to start over on this.

I appreciate the replies; this is a very frustrating issue when you don't know what you don't know.

-Chris

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